Re: arch/powerpc/kernel/optprobes.c:34:1: error: unused function 'is_kprobe_ppc_optinsn_slot'

[Christophe Leroy <christophe.leroy@csgroup.eu>]

Le 11/05/2021 à 20:46, Nathan Chancellor a écrit :
> On 5/11/2021 9:47 AM, Christophe Leroy wrote:
>> Hi All,
>>
>> Le 11/05/2021 à 18:30, kernel test robot a écrit :
>>> Hi Christophe,
>>>
>>> First bad commit (maybe != root cause):
>>>
>>> tree: https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git master
>>> head:   1140ab592e2ebf8153d2b322604031a8868ce7a5
>>> commit: eacf4c0202654adfa94bbb17b5c5c77c0be14af8 powerpc: Enable OPTPROBES on PPC32

Ok, the problem appears on PPC32 with that patch, but it must have been there on PPC64 since the 
implementation of optprobes with commit 51c9c0843993 ("powerpc/kprobes: Implement Optprobes")


>>> date:   3 weeks ago
>>> config: powerpc-randconfig-r033-20210511 (attached as .config)
>>> compiler: clang version 13.0.0 (https://github.com/llvm/llvm-project 
>>> a0fed635fe1701470062495a6ffee1c608f3f1bc)
>>
>> A clang issue ?
>>
>>
>>> reproduce (this is a W=1 build):
>>>          wget https://raw.githubusercontent.com/intel/lkp-tests/master/sbin/make.cross -O 
>>> ~/bin/make.cross
>>>          chmod +x ~/bin/make.cross
>>>          # install powerpc cross compiling tool for clang build
>>>          # apt-get install binutils-powerpc-linux-gnu
>>>          # 
>>> https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?id=eacf4c0202654adfa94bbb17b5c5c77c0be14af8 
>>>
>>>          git remote add linus https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git
>>>          git fetch --no-tags linus master
>>>          git checkout eacf4c0202654adfa94bbb17b5c5c77c0be14af8
>>>          # save the attached .config to linux build tree
>>>          COMPILER_INSTALL_PATH=$HOME/0day COMPILER=clang make.cross W=1 ARCH=powerpc
>>>
>>> If you fix the issue, kindly add following tag as appropriate
>>> Reported-by: kernel test robot <lkp@intel.com>
>>>
>>> All errors (new ones prefixed by >>):
>>>
>>>>> arch/powerpc/kernel/optprobes.c:34:1: error: unused function 'is_kprobe_ppc_optinsn_slot' 
>>>>> [-Werror,-Wunused-function]
>>>     DEFINE_INSN_CACHE_OPS(ppc_optinsn);
>>>     ^
>>>     include/linux/kprobes.h:306:20: note: expanded from macro 'DEFINE_INSN_CACHE_OPS'
>>>     static inline bool is_kprobe_##__name##_slot(unsigned long addr)        \
>>
>> That's a 'static inline', shouldn't generate an 'unused function' warning.
> This is a W=1 build, which means that "inline" does not silence unused function warnings with clang 
> because of commit 6863f5643dd7 ("kbuild: allow Clang to find unused static inline functions for W=1 
> build").

Ok, I didn't know that.

> 
> Cheers,
> Nathan
> 
>>>                        ^
>>>     <scratch space>:16:1: note: expanded from here
>>>     is_kprobe_ppc_optinsn_slot
>>>     ^
>>>     1 error generated.
>>>
>>>
>>> vim +/is_kprobe_ppc_optinsn_slot +34 arch/powerpc/kernel/optprobes.c
>>>
>>> 51c9c084399352 Anju T 2017-02-08  20
>>> 51c9c084399352 Anju T 2017-02-08  21  #define TMPL_CALL_HDLR_IDX    \
>>> 51c9c084399352 Anju T 2017-02-08  22 (optprobe_template_call_handler - optprobe_template_entry)
>>> 51c9c084399352 Anju T 2017-02-08  23  #define TMPL_EMULATE_IDX    \
>>> 51c9c084399352 Anju T 2017-02-08  24 (optprobe_template_call_emulate - optprobe_template_entry)
>>> 51c9c084399352 Anju T 2017-02-08  25  #define TMPL_RET_IDX        \
>>> 51c9c084399352 Anju T 2017-02-08  26      (optprobe_template_ret - optprobe_template_entry)
>>> 51c9c084399352 Anju T 2017-02-08  27  #define TMPL_OP_IDX        \
>>> 51c9c084399352 Anju T 2017-02-08  28 (optprobe_template_op_address - optprobe_template_entry)
>>> 51c9c084399352 Anju T 2017-02-08  29  #define TMPL_INSN_IDX        \
>>> 51c9c084399352 Anju T 2017-02-08  30      (optprobe_template_insn - optprobe_template_entry)
>>> 51c9c084399352 Anju T 2017-02-08  31  #define TMPL_END_IDX        \
>>> 51c9c084399352 Anju T 2017-02-08  32      (optprobe_template_end - optprobe_template_entry)
>>> 51c9c084399352 Anju T 2017-02-08  33
>>> 51c9c084399352 Anju T 2017-02-08 @34  DEFINE_INSN_CACHE_OPS(ppc_optinsn);
>>> 51c9c084399352 Anju T 2017-02-08  35
>>>
>>> :::::: The code at line 34 was first introduced by commit
>>> :::::: 51c9c0843993528bffc920c54c2121d9e6f8b090 powerpc/kprobes: Implement Optprobes
>>>
>>> :::::: TO: Anju T <anju@linux.vnet.ibm.com>
>>> :::::: CC: Michael Ellerman <mpe@ellerman.id.au>
>>>
>>> ---
>>> 0-DAY CI Kernel Test Service, Intel Corporation
>>> https://lists.01.org/hyperkitty/list/kbuild-all@lists.01.org
>>>
>>